gss-genr.c

   1 /* $OpenBSD: gss-genr.c,v 1.10 2006/04/03 07:10:38 djm Exp $ */
   2
   3 /*
   4  * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #ifdef GSSAPI
  30
  31 #include "xmalloc.h"
  32 #include "bufaux.h"
  33 #include "log.h"
  34 #include "ssh2.h"
  35
  36 #include "ssh-gss.h"
  37
  38 extern u_char *session_id2;
  39 extern u_int session_id2_len;
  40
  41 /* Check that the OID in a data stream matches that in the context */
  42 int
  43 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
  44 {
  45         return (ctx != NULL && ctx->oid != GSS_C_NO_OID &&
  46             ctx->oid->length == len &&
  47             memcmp(ctx->oid->elements, data, len) == 0);
  48 }
  49
  50 /* Set the contexts OID from a data stream */
  51 void
  52 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
  53 {
  54         if (ctx->oid != GSS_C_NO_OID) {
  55                 xfree(ctx->oid->elements);
  56                 xfree(ctx->oid);
  57         }
  58         ctx->oid = xmalloc(sizeof(gss_OID_desc));
  59         ctx->oid->length = len;
  60         ctx->oid->elements = xmalloc(len);
  61         memcpy(ctx->oid->elements, data, len);
  62 }
  63
  64 /* Set the contexts OID */
  65 void
  66 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid)
  67 {
  68         ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length);
  69 }
  70
  71 /* All this effort to report an error ... */
  72 void
  73 ssh_gssapi_error(Gssctxt *ctxt)
  74 {
  75         char *s;
  76
  77         s = ssh_gssapi_last_error(ctxt, NULL, NULL);
  78         debug("%s", s);
  79         xfree(s);
  80 }
  81
  82 char *
  83 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status,
  84     OM_uint32 *minor_status)
  85 {
  86         OM_uint32 lmin;
  87         gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
  88         OM_uint32 ctx;
  89         Buffer b;
  90         char *ret;
  91
  92         buffer_init(&b);
  93
  94         if (major_status != NULL)
  95                 *major_status = ctxt->major;
  96         if (minor_status != NULL)
  97                 *minor_status = ctxt->minor;
  98
  99         ctx = 0;
 100         /* The GSSAPI error */
 101         do {
 102                 gss_display_status(&lmin, ctxt->major,
 103                     GSS_C_GSS_CODE, GSS_C_NULL_OID, &ctx, &msg);
 104
 105                 buffer_append(&b, msg.value, msg.length);
 106                 buffer_put_char(&b, '\n');
 107
 108                 gss_release_buffer(&lmin, &msg);
 109         } while (ctx != 0);
 110
 111         /* The mechanism specific error */
 112         do {
 113                 gss_display_status(&lmin, ctxt->minor,
 114                     GSS_C_MECH_CODE, GSS_C_NULL_OID, &ctx, &msg);
 115
 116                 buffer_append(&b, msg.value, msg.length);
 117                 buffer_put_char(&b, '\n');
 118
 119                 gss_release_buffer(&lmin, &msg);
 120         } while (ctx != 0);
 121
 122         buffer_put_char(&b, '\0');
 123         ret = xmalloc(buffer_len(&b));
 124         buffer_get(&b, ret, buffer_len(&b));
 125         buffer_free(&b);
 126         return (ret);
 127 }
 128
 129 /*
 130  * Initialise our GSSAPI context. We use this opaque structure to contain all
 131  * of the data which both the client and server need to persist across
 132  * {accept,init}_sec_context calls, so that when we do it from the userauth
 133  * stuff life is a little easier
 134  */
 135 void
 136 ssh_gssapi_build_ctx(Gssctxt **ctx)
 137 {
 138         *ctx = xcalloc(1, sizeof (Gssctxt));
 139         (*ctx)->context = GSS_C_NO_CONTEXT;
 140         (*ctx)->name = GSS_C_NO_NAME;
 141         (*ctx)->oid = GSS_C_NO_OID;
 142         (*ctx)->creds = GSS_C_NO_CREDENTIAL;
 143         (*ctx)->client = GSS_C_NO_NAME;
 144         (*ctx)->client_creds = GSS_C_NO_CREDENTIAL;
 145 }
 146
 147 /* Delete our context, providing it has been built correctly */
 148 void
 149 ssh_gssapi_delete_ctx(Gssctxt **ctx)
 150 {
 151         OM_uint32 ms;
 152
 153         if ((*ctx) == NULL)
 154                 return;
 155         if ((*ctx)->context != GSS_C_NO_CONTEXT)
 156                 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER);
 157         if ((*ctx)->name != GSS_C_NO_NAME)
 158                 gss_release_name(&ms, &(*ctx)->name);
 159         if ((*ctx)->oid != GSS_C_NO_OID) {
 160                 xfree((*ctx)->oid->elements);
 161                 xfree((*ctx)->oid);
 162                 (*ctx)->oid = GSS_C_NO_OID;
 163         }
 164         if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
 165                 gss_release_cred(&ms, &(*ctx)->creds);
 166         if ((*ctx)->client != GSS_C_NO_NAME)
 167                 gss_release_name(&ms, &(*ctx)->client);
 168         if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
 169                 gss_release_cred(&ms, &(*ctx)->client_creds);
 170
 171         xfree(*ctx);
 172         *ctx = NULL;
 173 }
 174
 175 /*
 176  * Wrapper to init_sec_context
 177  * Requires that the context contains:
 178  *      oid
 179  *      server name (from ssh_gssapi_import_name)
 180  */
 181 OM_uint32
 182 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
 183     gss_buffer_desc* send_tok, OM_uint32 *flags)
 184 {
 185         int deleg_flag = 0;
 186
 187         if (deleg_creds) {
 188                 deleg_flag = GSS_C_DELEG_FLAG;
 189                 debug("Delegating credentials");
 190         }
 191
 192         ctx->major = gss_init_sec_context(&ctx->minor,
 193             GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
 194             GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
 195             0, NULL, recv_tok, NULL, send_tok, flags, NULL);
 196
 197         if (GSS_ERROR(ctx->major))
 198                 ssh_gssapi_error(ctx);
 199
 200         return (ctx->major);
 201 }
 202
 203 /* Create a service name for the given host */
 204 OM_uint32
 205 ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
 206 {
 207         gss_buffer_desc gssbuf;
 208         char *val;
 209
 210         xasprintf(&val, "host@%s", host);
 211         gssbuf.value = val;
 212         gssbuf.length = strlen(gssbuf.value);
 213
 214         if ((ctx->major = gss_import_name(&ctx->minor,
 215             &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name)))
 216                 ssh_gssapi_error(ctx);
 217
 218         xfree(gssbuf.value);
 219         return (ctx->major);
 220 }
 221
 222 /* Acquire credentials for a server running on the current host.
 223  * Requires that the context structure contains a valid OID
 224  */
 225
 226 /* Returns a GSSAPI error code */
 227 OM_uint32
 228 ssh_gssapi_acquire_cred(Gssctxt *ctx)
 229 {
 230         OM_uint32 status;
 231         char lname[MAXHOSTNAMELEN];
 232         gss_OID_set oidset;
 233
 234         gss_create_empty_oid_set(&status, &oidset);
 235         gss_add_oid_set_member(&status, ctx->oid, &oidset);
 236
 237         if (gethostname(lname, MAXHOSTNAMELEN)) {
 238                 gss_release_oid_set(&status, &oidset);
 239                 return (-1);
 240         }
 241
 242         if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) {
 243                 gss_release_oid_set(&status, &oidset);
 244                 return (ctx->major);
 245         }
 246
 247         if ((ctx->major = gss_acquire_cred(&ctx->minor,
 248             ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL)))
 249                 ssh_gssapi_error(ctx);
 250
 251         gss_release_oid_set(&status, &oidset);
 252         return (ctx->major);
 253 }
 254
 255 OM_uint32
 256 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
 257 {
 258         if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
 259             GSS_C_QOP_DEFAULT, buffer, hash)))
 260                 ssh_gssapi_error(ctx);
 261
 262         return (ctx->major);
 263 }
 264
 265 void
 266 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service,
 267     const char *context)
 268 {
 269         buffer_init(b);
 270         buffer_put_string(b, session_id2, session_id2_len);
 271         buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST);
 272         buffer_put_cstring(b, user);
 273         buffer_put_cstring(b, service);
 274         buffer_put_cstring(b, context);
 275 }
 276
 277 OM_uint32
 278 ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid)
 279 {
 280         if (*ctx)
 281                 ssh_gssapi_delete_ctx(ctx);
 282         ssh_gssapi_build_ctx(ctx);
 283         ssh_gssapi_set_oid(*ctx, oid);
 284         return (ssh_gssapi_acquire_cred(*ctx));
 285 }
 286
 287 #endif /* GSSAPI */